The reasoning is simple: fossil fuels can be burned to make energy, or used as a raw material (e.g. for production of plastics). Every barrel of oil we burn for energy is therefore a barrel which we can't use as a raw material. Thus:

Their burning — whenever they could have been replaced by renewables — is costly capital destruction.

The report concludes that the "future usage loss" resulting from current consumption is between $3.2trn and $3.4trn a year.

Roberts writes that "the exact numbers here are, like numbers in all economic modeling, probably going to turn out to be wrong," and he's definitely right. At first glance, the most important thing absent from the initial paper is no discussion of the difference between present and future value.

This isn't just the problem that resources worth $3.2trn at today's prices might not be worth that at tomorrow's; its also that rigorous economic analysis always discounts the future.

Consider it this way: if you had the option to be paid £100 now or £100 in a year, you would clearly choose the former. The money in the future is less valuable, even though it is nominally the same amount. That's partially because people want things now, of course; but it's also because if you took the £100 now and put it in a savings account, it would be worth more than £100 in 12 month's time. (And let's not even begin on the discussions of how new technology will change the value of fossil fuels as raw materials in ways we can't begin to predict. How will things change, for instance, if conductive plastics take off?)

The same thinking needs to be applied to the question of the "destruction" of potential resources. Their value today — and thus the degree to which they ought to encourage us to switch to renewables — is lower the further into the future we are going to use them.

But really, the discussion of the actual value is slightly moot. Unless we're doing a massive overview of the costs of climate change mitigation — a second Stern report — then we can't properly weigh those costs against all the others. What we can say is that this is an under-discussed benefit of switching to renewable technology sooner rather than later, and of promoting climate change prevention rather than mitigation.

If we build enough renewable energy capacity to supply our entire system, there are still fossil fuels ready to burn. The people who built the renewable capacity may not want to burn them – but what about the next government? Or the next generation?

One option is to prevent future irresponsibility by burning fossil fuels today but with carbon capture and storage, ensuring that the carbon goes back underground. But another option is to switch to renewables and then continue using the fossil fuels for material production, locking up carbon not in vaults underground but in plastics.

In that analysis, even landfills get an image rehabilitation. They become gigantic carbon sinks, encouraging further use of fossil fuels as raw materials, removing more and more potential atmospheric carbon from circulation. There's hope for everyone yet.